1. Field of the Invention
The present invention relates to an asymmetric hollow-fiber gas separation membrane made of a polyimide, having an excellent gas separation performance and an improved mechanical strength, wherein the polyimide is composed of a specific aromatic tetracarboxylic acid and an aromatic diamine.
2. Description of the Related Art
Patent Documents 1 and 2 disclose an asymmetric hollow-fiber gas separation membrane made of a polyimide, having an adequate ratio of permeation rate of oxygen to nitrogen gas, wherein the polyimide is formed from a specific aromatic tetracarboxylic acid and an aromatic diamine.
Patent Document 1: Japanese Patent Laid-Open Publication No. H03-267130
Patent Document 2: Japanese Patent Laid-Open Publication No. H06-254367